Pneumatic Actuator-Spring Return(Fail Safe)

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Sizing example of HAITIMA spring return actuator:
Spring to close when air fails(air to open):
Valve torque 60Nm plus 20% safety factor = 72Nm. Minimum operating pressure: 6bar(87psig). The spring return HAITIMA actuator selected is NKS-105-12.The NKS-105-12 has the following output torques:
1.air torque 0°(valve close) = 124Nm > 72Nm
2.air torque 90°(valve open) = 84Nm
3.spring torque 90 (valve open) = 120Nm
4.spring torque 0°(valve close) = 80Nm > 72Nm





The operating principle of single acting spring return actuator
Air to port A forces the pistons outwards, causing the springs to compress. The pinion turns counter-clockwise while air is being exhausted through port B.
Mounting Variations
Loss of air pressure through port A allows the stored energy in the springs to force the pistons inwards. The pinion turns clockwise while air is being exhausted through port A.
Spring Arrangement